[Amps] Capacitor and Alpha 374 question

[Ted]

     I have a three tube Alpha 374, it has an oil-filled capacitor rated 
at 40pf/5KV.  After running awhile in cw an AC hum occurs on my signal.  
I am thinking that after heating up this old oil-filled capacitor may be 
going bad and breaking down.  It seems impossible to find another such 
oil-filled capacitor so I bought a capacitor replacement kit from "Tube 
Meister."  The add says it is for Alpha/76/78/374.  I do have two other 
Alpha 374A amplifiers and the replacement kits are great.

     My question is since there are just two leads from the oil-filled 
capacitor can I just simply connect the 6 210pf/450 volt capacitors in 
series and run the leads to where the oil-filled capacitor connected?  
Am I missing some important step here?  I'd rather not blow the 374 up!  
Perhaps even someone might suggest where one finds an oil-filled 
40pf/5kv capacitor?

     Thanks for any help/suggestions.

73,

Ted K8AQM